Red Ear Sliders are not "bottom walkers" so it won't stay on the bottom. They love swimming, and can get quite large so a lot of swimming space is needed. They also absolutely NEED to bask to prevent shell rot and other not so nice medical conditions, including not digesting their food and eventually death. If you are concerned about your turtle, I recommend checking out either the Turtle Forum or the Tortoise Forum (they have a small turtle section), and then deciding if it needs to go to a vet. Most reptile specialty vets will check out your pet for 20-50 dollars, plus the cost of medications and tests.
flat bottom shell female, indented bottom shell male, he has to be able to stay mounted
There could be many reasons why your fish stay on the bottom. These include wrong water temperature, poor water condition, low oxygen content, etc etc. They could also be hiding from predatory birds or animals. More info is needed to be specific.
because land snails normally stay on land and pond snails stay in the water
Forever. How long can they stay alive underwater? It depends.
The water tension keeps them from sinking
5 minutes
Because they need food to stay alive.
Goldfish are moderately inactive fish. They will spend much of their time just floating or sitting at the bottom.
Yes, if the pond water is cold it won't bother them. They stay at the bottom of the pond even when the top is covered with ice. They come back to the surface when the Springtime temperature is 55 degrees. We have been raising Koi for six years. If you mean cold water from your kitchen sink, you have to put a treatment in the water so they won't die.
nope if they are in a small tank and it gets bigger put it in a larger tank
you stay at the bottom
statues of birds will usually deter an egret. also, your pond should be deep enough for the koi to stay out of range, at least 36 inches deep. i have rock ledges in my pond for the fish to hide under. if your pond has a ledge, fill it with plants so there is nowhere for the bird to stand.